Staple cutter and method



July 21, 1953.

R. w. PETERSON 2,646,121

STAPLE CUTTER AND METHOD Filed May 20, 1950 HVVENTUR.

AITZUQNESF Rqssell, WLZburPete/"sm Patented July 21, 1953 STAPLE CUTTER AND ,METHOD Russell Wilbur Peterson, Wilmington, Del., assignor to E. I. du Pont de .Nemours and Company, Wilmington, Del, a corporation of Delaware Application May 20, 1950, Serial No. 163,201

3 Claims.

This invention relates to a method and apparatus for the improved cutting of a bundle of artificial threads, filaments and the like to any desired length as the bundle is continuously fed from a spinning machine or other continuous filament supply.

Of the many methods and types of cutting apparatus proposed and/or used for the cutting of continuous artificial filaments into staple lengths, one of the most satisfactory has been that wherein the bundle of continuous filaments to be cut is subjected to the action of centrifugal force and is cut at right angles to the direction of said action. This is accomplished by passing the bundle of continuous filaments outwardly through a radial passageway provided in a rapidly rotating disc, the filaments being severed by a stationary cutter having its cutting edge located at the periphery of the disc. The desired length of cut is obtained by regulating the speed of the disc relative to the speed at which the yarn is fed to the disc.

This type of cutter however, does have one rather important drawback in that some of the filaments are frequently not severed by the knife. As a result, when these uncut filaments are cut on the next revolution, the result is long ends that are twice the length of the staple that is desired. This poor cutting is caused primarily by the dullness of the first knife and to a limited degree by air drag. Since the first knife seems to lose its high degree of sharpness at an appreciable rate upon continuous use, it is not surprising that some of the filaments hit thefirst knife and are not completely severed thereby.

Furthermore, as the rotor or disc rotates air drag on the tuft of filaments projecting from the periphery tends to make some of the filaments fiatten back against the rotor. These bent filaments do not, of course, strike the knife with the same degree of force as those which remain erect. As a consequence, the resultant cutting action is not nearly as good as occurs when the cutting blade of the knife hits the filaments squarely. The number of long ends is especially noticeable with some of the newer synthetic fibers, although even in cellulose acetate and viscose rayon fields the problem is troublesome. The presence of long endsin the staple makes it very difficult to work on the cotton system of spinning, thus decreasing to a certain extent the utility of the material, especially as staple for spun yarn.

The principal object of this invention therefore, is to provide improvements in method and apparatus for the centrifugal cutting of a bundle into the center 2. of continuous filaments whereby all filamentsin the bundle are cut to a'uniform length. This and other objects will more clearly appear hereinafter.

These objects are realized by the present invention which, briefly stated, comprises continuously feeding a bundle of continuous filaments through a centrifugal type cutter of the type hereinabove described and bringing filaments not out (i. e., missed), by the knife of said cutter into cutting contact with a second knife positioned to cut said. uncut filaments to the desired uniform length.

Several arrangements constituting preferred embodiments of the apparatus of. this invention will now be described with reference to the accompanying drawing wherein: V

Figure 1 is an elevational view of one embodiment of the invention. V

Figure 2 is a plan view of the same embodiment.

Figure 3 a plan view of another embodimentof the invention.

Referring to Figures 1 and '2: In the operation of this invention a tow or bundle of yarn 3 is fed hole it, of the rapidly rotating disc l2. Centrifugal force caused by the rapid rotation of disc It carries the tow 3 through the by the first knife I (position A).

radial passageway l3 to the periphery of the disc. As the tow emerges from the radial passageway it, it is cut into the desired staple length The arrangement thus far described is that of the prior art.

Any uncut filaments such as shown by 5 (position B) are cut by a second knife 2 (hereinafter called scavenger knife). The rate of feed of tow to the disc and the rotative speed of the disc are so adjusted that the tow advances an amount equal to the length of staple being out per revolution of the rotating disc. The scavenger knife 2 is positioned from the periphery of the disc 52 a distance 6 which is greater than the distance 5 of the first knife i from the periphery, byan amount sufficient to compensate for advance of the tow as the peripheral outer opening for the passageway [3 moves from position A to position B, whereby the uncut filaments A will have thesame length as the rest of the staple fiber when severed by the scavenger knife 2.

Referring to Figure 3: The operation with respect to the feed and advance of the tow is the same as described previously. However, in this embodiment the second or scavenger knife It is placed beside knife I and on the same radial line with respect to disc l2, the distance ll, between the knives coinciding with the length of the staple being cut. The first cut on the tow is made by the knife I; then as the disc l2 makes one complete revolution, the ends missed by the first knife, are severed by scavenger knife i0, and simultaneously additional staple is cut from the tow by knife I.

The knives may obviously be placed at desired angles so that different degrees of shearing action and slicing action may be accomplished. For example, both knives may be mounted on the original knife holder parallel to one another (Figure 1 shows the knives sloped in opposite directions). Some slight adjustment may be necessary in any given installation to be assured of the best cutting action. Further, the knives may be the circular type so that more cutting surface is available for use before resharpening is necessary. And again the knives may be made from any one of a number of steels and other alloys that are especially recommended for use as cutting tools.

The principle of this invention is, of course, not restricted in application to the specific embodiments hereinabove described. It is obvious, for example, that other pairs of knives may be evenly spaced around the periphery of the disc so that two or more cuts per revolution may be made. Furthermore, the invention is not to be considered as involving the use of a single scavenger knife, since a plurality of scavenger knives may prove advantageous in certain operations.

The decrease in long end count as a direct result of the use of the scavenger knife is clearly demonstrated by three series of experiments, the essential data of which are tabulated in the following table: (The rotative speed of the disc is 3450 R. P. M. in all cases.)

I II III Rate of Tow Feed (inches/remind 13 10 15 2 Output (lbs/hr.) i. 190 270 360 Length of Staple (inches) 1M5 13 2 Long ends/80 grains of fibers:

Without scavenger knife LOGO-3,000 30-200 30-150 With scavenger knife 7-10 As many widely different embodiments may be made without departing from the spirit and scope of my invention, it is to be understood that said invention is in no Way restricted except as set forth in the appended claims.

I claim:

1. In apparatus for cutting staple fibers from a bundle of continuous filaments comprising rotating means for feeding the end portion of the bundle axially at a uniform rate and in a spiral path by the action of centrifugal forces and cutting means arranged at a fixed position in the path of said bundle for cutting the bundle into fibers of uniform length, the improvement which comprises additional cutting means disposed at a second fixed position in the path or said bundle, said second position being in the same spiral path as said first cutting means so as to cut filaments missed by said first named cutting means at substantially the same point in said bundle.

2. In apparatus for cutting staple fibers from a bundle of continuous filaments comprising a rotatable disc, a radial passageway therein terminating at the periphery of the disc and adapted to feed the end portion of the bundle axially at a uniform rate and in a spiral path by the action of centrifugal forces, and a stationary cutter having its cutting edge positioned at the periphery of said disc, the improvement which comprises a second stationary cutter having its cutting edge positioned in the path of said bundle in the same spiral path as said first cutter so as to cut filaments missed by said first named cutting means at substantially the same point on said bundle.

3. In a method for cutting staple fibers from a bundle of continuous filaments wherein the end portion of said bundle is fed by a rotating means axially at a uniform rate and in a spiral path by centrifugal action to a cutting means fixed at an angle to the direction of said centrifugal action for cutting said fibers into a uniform length, the improvement which comprises feeding the end portion of said bundle to a second cutting means fixed in the same spiral path as the first cutting means so as to out filaments missed by said first named cutting means at substantially the same point in said bundle.

RUSSELL WILBUR PETERSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,232,496 Thompson Feb. 18, 1941 2,296,252 Bitler Sept. 22, 1942 2,323,644 Castellan Jul 6, 1943 2,424,555 Curtis July 29, 1947 

